Iwerks Entertainment Inc. has signed an agreement with Japan's Itochu Corp. to provide hardware for a second Cinetropolis movie complex in a shopping mall now under construction in Chiryu, Japan. Burbank-based Iwerks aims to build a global network of these entertainment centers featuring films and virtual reality attractions. The exact value of the agreement was not released. Iwerks said only that its worth was in the millions of dollars.

Private equity firm KKR & Co. LP and three partners say they have agreed to buy the privately held oil and gas company Samson Investment Co. for $7.2 billion In the deal announced Wednesday, KKR and its partners will get access to oil and gas assets in booming shale regions in the U.S., including shale formations that contain large amounts of oil and other liquid hydrocarbons. Samson's wells in the deep water Gulf of Mexico and along the Gulf Coast are not included in the deal.

Steven F. Hallsey has been appointed president of property management for Western National Group, an Orange-based property management and development company. He is responsible for the day-to-day management of more than 26,000 apartment properties in Southern California and for overseeing the operations of RGS, a maintenance services company. Hallsey was previously president of Harbor Group Real Estate Co. in Norfolk, Va.

Mazda Motor Corp. said Thursday it has boosted its stake in Mazda Motor of America Inc. to 88% from 50% in a bid to strengthen the financial structure of the car maker's U.S. marketing subsidiary. The Japanese car maker, 33% owned by Ford Motor Co., said it is investing $126 million in the subsidiary by acquiring 5.63 million new shares.

Atlantic Richfield Co. said Tuesday that it is considering withdrawing from the coal mining business to focus on its main business of petroleum production, refining and retail fuel sales. Los Angeles-based Arco's coal assets totaled $1.75 billion worldwide at the end of 1996. The assets are concentrated in the U.S., where Arco is the fourth-largest coal producer, and in Australia.